"Are you saying there's happiness that begins with a broken engagement? My dear sister. Did you know that revenge begins with dinner?"

When her mother died in her childhood, Eugenia, a young noblewoman, has been managing the household for her unreliable father and younger sister. However, she is called plain and dull, constantly compared to her glamorous sister, and even mocked as a boring woman by her own sister. When such Eugenia is chosen as the fiancée of the crown prince, her sister, consumed by jealousy, has her annulled from the engagement on false charges and exiled to a convent. What action does Eugenia take to get revenge on her sister and the crown prince?